A polar bear swam continuously for over nine days, covering 687km (426 miles), a new study has revealed.

Scientists studying bears around the Beaufort sea, north of Alaska, claim this endurance feat could be a result of climate change. Polar bears are known to swim between land and sea ice floes to hunt seals.

But the researchers say that increased sea ice melts push polar bears to swim greater distances, risking their own health and future generations.

In prior decades, before 1995, low-concentration sea ice persisted during summers over the continental shelf in the Beaufort Sea. This means that the distances, and costs to bears, to swim between isolated ice floes or between sea ice and land was relatively small. The extensive summer melt that appears to be typical now in the Beaufort Sea has likely increased the cost of swimming by polar bears.